The effects of nitrous oxide and oxygen on transient hyperemic response in human volunteers
The effects of nitrous oxide and oxygen on transient hyperemic response in human volunteers
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DOI：
10.1097/00000539-199907000-00031
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发表时间：
1999-07-01
影响因子：
5.7
通讯作者：
Mahajan, RP
中科院分区：
文献类型：
--
作者：
Girling, KJ;Cavill, G;Mahajan, RP
本研究的目的是确定呼吸100%氧气或50%氧化亚氮对人类志愿者短暂性充血反应（THR）试验得出的大脑自动调节指标的影响。数据分析来自9名健康受试者。经颅多普勒超声测定大脑中动脉血流速度（MCA），压迫颈总动脉10s进行THR试验。连续测量PETCO2，以及氧气FETO2和一氧化二氮（FETN2O）的过期分数，每隔2分钟记录平均动脉压（MAP）。在志愿者呼吸室内空气时进行AU测量，并在FETO2达到0.95后10分钟和FETO2达到0.48-0.52后10分钟重复测量。从THR试验中得出的两个指标，即短暂充血反应比（THRR）和自动调节强度（SA），用于评估大脑自动调节。PETCO2和平均动脉压在整个研究期间没有明显变化。呼吸100%氧气对MCA FV、THRR和SA没有影响。吸入一氧化二氮导致MCA FV显著增加（从48 +/- 9增加到72 +/- 8 cm/s，平均+/- so）， THRR（从1.5 +/- 0.2到1.2 +/- 0.1）和SA（从1.0 +/- 0.1到0.8 +/- 0.1）显著降低（P < 0.05）。我们的结论是，在氧气中吸入50%的氧化亚氮会导致MCA FV的显著增加和短暂充血反应的损害。意义：我们的研究表明，一氧化二氮会损害大脑的自动调节，这可能对其在神经外科麻醉中的应用以及对一氧化二氮作为背景使用的麻醉药研究结果的解释有影响。
The aim of this study was to determine the effects of breathing 100% oxygen or 50% nitrous oxide in oxygen on the indices of cerebral autoregulation derived from the transient hyperemic response (THR) test in human volunteers. Data were analyzed from nine healthy subjects. Middle cerebral artery (MCA) blood flow velocity (FV) was measured by transcranial Doppler ultrasound, and the THR test was performed using 10-s compression of the common carotid artery. Continuous measurement of PETCO2, and expired fractions of oxygen FETO2 and nitrous oxide (FETN2O) was established, and mean arterial pressure (MAP) was recorded at 2-min intervals. AU measurements were performed while the volunteers were breathing room air and were repeated 10 min after achieving FETO2 > 0.95 and 10 min after achieving FETN2O 0.48-0.52. Two indices derived from the THR test, the transient hyperemic response ratio (THRR) and strength of autoregulation (SA), were used to assess cerebral autoregulation. PETCO2 and mean arterial pressure did not change significantly throughout the study period. Breathing 100% oxygen did not change MCA FV,THRR, or SA. Inhalation of nitrous oxide resulted in a marked and significant increase in the MCA FV (from 48 +/- 9 to 72 +/- 8 cm/s; mean +/- so) and a significant decrease in the THRR (from 1.5 +/- 0.2 to 1.2 +/- 0.1) and the SA (from 1.0 +/- 0.1 to 0.8 +/- 0.1) (P < 0.05 for all). We conclude that breathing 50% nitrous oxide in oxygen results in both a significant increase in MCA FV and impairment of transient hyperemic response. Implications: Our study suggests that nitrous oxide impairs cerebral autoregulation and may have implications for its use in neurosurgical anesthesia and for interpretation of the results from studies of anesthetics in which nitrous oxide is used in the background.